The Ecologically Chemical Detoxification Behaviors Of Copper-Pesticides Pollution In Soil

Through carrying out of the experiments of heavy metal copper and insecticide methamidophos, herbicide glyphosate sorption/desorption behaviors, the experiments of copper and methamidophos environmental behavior in soybean rhizosphere, and the experiments of the ecologically chemical indication of pesticides detoxification (soil enzyme, available P), we studied the chemical detoxification behaviors of these pollutants in typical soils of northeastern China-phaiozem and burozem, and aimed to provide theory references for green agriculture base constructing in the area.Sorption/desorption behavior of the pollutants is the reflection of soil physical and chemical detoxification by itself. Experiments showed that the isothermal curves of Cu sorption/desorption in phaiozem and burozem were well fitted the Freundlich equation. The amount of Cu sorbed by phaiozem was much higher than that by burozem, but the desorption ratio was less than the latter. The relationships between desorption and Cu sorbed on the soils was well described by quadratic function. The best model for Cu sorption/desorption kinetics was two-constant equation.The isothermal curves of pesticides sorption on soils and soils removed organic matter were also well fitted the Freundlich equation. The organic matter removal made the sorption of the two pesticides much lowered. Inorganic minerals are main sorption carrier for methamidophos, but organic matter is more important in glyphosate sorption and detoxification process than other constituents. Meanwhile, the addition of the pesticides into the soils changed Cu sorption/desorption behavior, made Cu sorption decreased, and desorption increased. The effects of glyphosate were larger than that of methamidophos because of stronger complex ability with Cu.The pollutants are detoxified under biochemical mechanism by rhizosphere and soil enzyme. Through transformed the Cu into iron/manganese oxide and organic matter bound in rhizosphere, soybean decreased the Cu absorption. The degradation of methamidophos was evidently accelerated in the soybean rhizosphere. Soil dehydrogenase was sensitive to the two pesticides, and its activity was inhibited in most cases. Acidic phosphatase was stimulated in the first stage of methamidophos addition, followed by partially inhibited, and the higher glyphosate concentration, the greater inhibition of enzyme activity. Soil available P was increased after the two pesticides were added. But the contribution ratio of degradation products to available P was low.